- var_export: documentation ( source)
- strtoupper: documentation ( source)
<?php
$strings = [
"test string",
"lado lomidze needs a solution",
"i made some research and found 'good' answers here; they really helped me."
]; // if not already all lowercase, use strtolower()
foreach ($strings as &$string) {
for ($i = 0, $len = strlen($string); $i < $len; $i += 2) {
$string[$i] = strtoupper($string[$i]);
}
}
var_export($strings);